# Disconnect Switch: Learn the Purpose, Cost, and Lead Time to Procure

#### Purpose of disconnect switch

• Disconnect switches establish isolation points for equipment maintenance. They are installed on both sides of the circuit breaker, high-side of the transformer, and on the line exit.
• Switches cannot and should not be used to interrupt load current or fault current. A switch operation takes place after the circuit is de-energized.

#### Cost of disconnect switch

A switch can be designed numerous ways – vertical break, center break, side break, double side break, pantograph, etc. View some of them here. The style you want depends on how the substation bus is laid out. The prices below reflect your typical vertical break configuration.

• 15kV 600A/1200A disconnect switch with manual operator: ~$7,000 • 35kV 1200A disconnect switch with manual operator: ~$7,000
• 69kV 1200A disconnect switch with manual operator: ~$14,000 • 138kV 2000A disconnect switch with motor operator: ~$20,000
• 230kV 3000A disconnect switch with motor operator: ~$33,000 • 345kV 3000A disconnect switch with motor operator: ~$66,000
• 500kV 3000A disconnect switch with motor operator: ~$102,000 • 765kV 3000A disconnect switch with motor operator: ~$150,000

Note: The cost includes the price of structural steel. For 138kV and above, the price of steel for high switch stand used (for conservative figures).

#### Lead time to procure disconnect switch

~22 weeks for a high voltage switch.

Information on cost and lead time is for your general knowledge only. Contact vendor with your equipment specifications for actual figures.

##### Attempt the quiz
/7

Substation Major Equipment

It's only stupid-simple, let's begin.

###### A transformer develops an internal fault. Which device would you install on the transformer high-side to interrupt fault current?

The average score is 46%

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### 2 thoughts on “Disconnect Switch: Learn the Purpose, Cost, and Lead Time to Procure”

1. I am having strong RFI from a local power company in Mesa, Arizona (SRP) and they think that it may be due to the Disconnect Switches they are using. Is that typical for these products since they operate at very high voltages? I am a Ham Operator and am receiving considerable RFI on the 3.5-7.5 mhz frequency bands. Any suggestions on how I might be able to prevent that from getting into my antenna system? Their Substation is about 1/2 block from my location.

Regards,
Doug Willoughby, K7GJX

1. Corona discharge from EHV conductors can cause radio interference. What voltage is the substation? Substation design standards require corona mitigation at extra high voltages (345kV and above).
Corona discharge is absolutely possible during EHV switch operation. But switch operation happens occasionally. So, if it’s a consistent interference then it’s something else.

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